PMB exam 2

Dinophyta: The Dinoflagellates

2,000 - 4,000 Species • Marine and freshwater • Unicellular Nutrition & Photosynthesis • Autotropic (~ 50% of species) or Mixotrophic, or Heterotrophic • Chlorophyll a and c

parenchyma

Parenchymatous algae have meristems from which cell division can occur in any plane, resulting in three-dimensional growth and true tissues

Angiosperm Diversity

200-250 Million Years Ago Sudden appearance of abundant and diverse angiosperms in the Cretaceous New fossil pollen evidence pushes the date back to 250 mya, perhaps At least 300,000 species!! The angiosperm radiation competitively excluded the gymnosperms

Shoots Are Somewhat More Complex Than Roots

Shoots have nodes and internodes with leaves at each node Axillary buds develop into lateral shoots (branches) The root apex does not produce lateral organs like leaves (just lateral roots)

Secondary Growth from Secondary Meristems

Vascular Cambium: Produces secondary xylem and secondary phloem Formation of Secondary Xylem (Wood) and Secondary Phloem from a Vascular Cambium (pith in center, surrounded by secondary xylem, the vascular cambium, then secondary phloem) Cork Cambium: Produces the periderm Cork Cambium Makes the Secondary Dermal Tissue, Periderm (vascular cambium, living phloem, periderm (cork cambium and then cork) bark made of phloem and periderm Bark cracks, flakes, and sloughs as the tree grows laterally

Megagametophyte Structure & Development

divides 3 times resulting in a cell with 8 nuclei • cell walls form 7 cells • one cell has 2 nuclei, called polar nuclei • note, angiosperms do not have archegonia Gymnosperms: integument surrounds megasporangium, has 4 megaspores. 1 megaspore germinates into the megagametophyte, has an archegonia where it makes eggs Angiosperms: integument surrounds megasporangium, has 4 megaspores. 1 megaspore divides into the 7 cells

endophyte transmission methods

horizontal transmission: between individuals that are not linked by a parent child relationship (most endophytes) vertical transmission: from mother to offspring (endophytes in many grasses)

Chlorophyll - Green Pigments

Pigments are essential for absorbing light for photosynthesis Accessory pigments broaden the scope of light absorbed Chlorophyll a is found in every photosynthetic eukaryote Chlorophyll b is an accessory pigment found in green algae and land plants. Accessory pigments transfer energy to chlorophyll a Chlorophyll c is an accessory pigment found in marine algae (this lecture). It essentially fills the same role as chlorophyll b (absorbs similar wavelengths)

haptophyte structure

• 2 flagella + a haptonema (other cytoskeletal organelle, not for motility- looks like a smaller flagella) • Haptonema can sometimes assist with catching prey food • Some are covered with calcified scales called 'coccoliths' (and called 'coccolithophorids') Coccoliths may be secreted through the Golgi bodies or made at the cell surface Coccoliths composed of calcium carbonate Single largest component of deep sea sediments

What are the functions of roots?

• Anchorage • Water absorption • Nutrient absorption • Interactions with soil microorganisms • Nutrient storage

CAM Plants Crassulacean Acid Metabolism

• C4 pathway and Calvin cycle are separated in TIME, not space • CAM Pathway is adaptation to dry conditions; can close stomata in day • Leaves are frequently succulent • Temporal, not spatial, separation of pathways • C4 at night, C3 in day (stores 4-C malate in vacuoles until day time)

C4 Pathway

• C4 pathway is a solution to photorespiration (enzyme has higher affinity for CO2) • First fixed C structures are C4 compounds created by PEP Carboxylase (c4 cycle) • Carbon is first fixed in mesophyll and 4-carbon compounds are funneled to bundle sheath for Calvin cycle • Pathway evolved in tropics (adaptation to high light, high temperatures, dryness) • Energy expensive because of extra steps

Photosynthetic characteristics of red algae

• Chloroplasts have unstacked thylakoids, with phycobilisomes • Like cyanobacteria, they have chlorophyll a, plus phycobilins that help absorb blue-green light that penetrates deep water. • The phycobilins mask the color of chlorophyll a and give red algae a red color

Life cycle of a centric diatom, such as Cyclotella

• No alternation of generations • Gametic meiosis, diploid dominant • Gametes are the haploid phase • Male gametes have heterokont flagella Gametes are release and fertilization occurs to form Auxospore (or zygote), auxospore divides asexually and gets smaller with the divisions, once it gets too small it releases gametes

Double Fertilization

• One sperm nucleus fuses with egg • The other sperm nucleus fuses with the 2 polar nuclei key innovation only found in Angiosperms Double Fertilization Is Common In Some Gnetophytes But A Bit Different

Function of Root Hairs (Root Epidermis)

• Single-celled extension produced by epidermal cells Greatly increase surface area of root. • Function in nutrient uptake.

Haptophyta - Coccolithophores

• ~300 species • Marine, freshwater, terrestrial • Unicellular and colonial Nutrition & photosynthesis • Autotrophic, mixotrophic • Chlorophyll a, c Thomas Huxley, famed British naturalist discovered these organisms in marine sediments in 1858 What Do Coccoliths Have To Do With Chalk And The White Cliffs Of Dover?

Characteristics of Red Algae

• ~5,000 species • Small genomes with few introns • Mainly marine species, a few freshwater • (Most) lack flagellated cells

Biodiversity of plants

# of species described Flowering plants: 300,000 Ferns: 12,000 Red and green algae: 10,000 Fungi: 100,000

Brown Algae - Phaeophyta

'heterokont' gametes and zoospores • 1,500 species • Mostly marine, in temperate and cold waters • Filamentous and morphologically complex thalli • Diverse life cycles Ectocarpus (at left) is one of the simplest of the brown algae, a branched filament

Brown Algae - Life Cycles

(most have sporic meiosis, some gametic meiosis) Laminaria - Sporic Meiosis Has a conspicuous sporophyte and inconspicuous gametophytes Fucus - Gametic Meiosis Has only a sporophyte and gametes

What are the oldest Angiosperm lineages?

- gymnosperm outgroup - Amborella trichopoda - Nymphaeaceae (Water Lilies & Relatives) - Austrobaileyales (Star Anise & Relatives) - Magnoliidae (Magnolias & Relatives) - Monocots - Eudicots Water lilies, star anise, and magnolias are basal angiosperms, considered dicots

Fertilization in angiosperms

After pollination, pollen germinates and the mature male gametophyte grows to the female gametophyte 2 sperm cells, one tube cell Tube nucleus controls pollen tube growth Pollen tubes are attracted to egg by signal secreted by synergids Once the pollen tube reaches the ovule the synergids induce the rupture of the pollen tube to release the sperm

Angiosperm Pollen

Angiosperm pollen at maturity has 3 cells! A very small male gametophyte! Gymnosperm pollen is very similar but at maturity has 5 cells

Bee pollination syndrome

Anithesis (when it opens): day colors: yellow, blue, purple, UV patterns odors: light sweet scent rewards: pollen and nectar

bat pollination syndrome

Anithesis (when it opens): night colors: dull white or green odors: strong, fermented rewards: ample nectar

Dichogamy

Anthers and stigma mature at different times (just like the archegonia and antheridia of ferns!)

Which of the following is TRUE about Angiosperm phylogeny? A. The monocots form a paraphyletic group B. The earliest-diverging lineage is Amborella trichopoda C. The dicots form a monophyletic group D. The monocots have more species than the eudicots E. The orchids and grasses are two of the "basal dicot" lineages

B. The earliest-diverging lineage is Amborella trichopoda

Border Cells and their Functions

Border Cells (a.k.a. sloughed root cap cells) • Are metabolically active, can divide • Secrete carbohydrate-rich mucilage • protection from biotic and abiotic challenges

Which of the following is FALSE about fungal endophytes? A. Endophytes are usually asymptomatic B. Endophyte species richness is greater in the tropics than the arctic C. Endophytes are most often vertically transmitted D. Endophytes use carbon produced by the plant E. Endophytes can reduce damage from herbivores

C. Endophytes are most often vertically transmitted

Which is False about Rhodelphidia, the newly-described phylum of Rhodophyta? A. They are non-photosynthetic and gain energy via phagotrophy B. They have flagellated cells at some point in the life cycle C. They arose via secondary endosymbiosis D. They have a gene-rich genome with many introns E. They are phylogenetically sister to the rest of the Rhodophyta

C. They arose via secondary endosymbiosis

dinoflagellate structure

Cell surface often made up of cellulose plates (theca) • Two flagella: one in transverse groove, one trailing • Beat of flagella makes cells SPIN

Climate Change & Seasonal Phenology

Colorado Rocky Mountains David Inouye Professor Emeritus, U. of Maryland Initially worked on pollinators, and as part of that work began documenting the flowering time of plants Fortuitously, this allowed him to later ask questions about climate change that occurred over the period of his long-term research Essence is that spring peak occurred earlier in the year, summer peak about the same, and last peak slightly later. Growing season length has increased through the years

George Washington Carver

Considered the most prominent black scientist of the early 20th century Born into slavery, earned PhD from Iowa State and became Professor at Tuskegee Institute Developed techniques to improve soils depleted by repeated plantings of cotton, especially peanuts and sweet potato Championed environmental sustainability, agricultural conservation, and self sufficiency As Carver rode the train to Alabama, however, his heart sank. In a 1941 radio broadcast, he recalled: "My train left the golden wheat fields and the tall green corn of Iowa for the acres of cotton, nothing but cotton, ... ... The scraggly cotton grew close up to the cabin doors; a few lonesome collards, the only sign of vegetables; stunted cattle, boney mules; fields and hill sides cracked and scarred with gullies and deep ruts ... Not much evidence of scientific farming anywhere. What Carver understood was that cotton, while lucrative, did nothing to replenish the soil. It's not the most demanding crop, but its shallow roots, and the practice of monocropping, mean that soil erodes faster from a cotton field than if the earth was left alone. (Carver later would describe eroded gullies on the Tuskegee campus that were deep enough for a person to stand inside.)

Which of the following is TRUE about growth and differentiation of the root? A. Border cells are dead cells sloughed off from the root cap, which have no special function B. The root cap is the apical meristem of the root C. Roots have nodes, internodes, and lateral organs D. Root hairs are single celled extensions produced by epidermal cells E. Roots contain stomates, which regulate gas exchange

D. Root hairs are single celled extensions produced by epidermal cells

Which of these statements about the Phaeophyta (Brown Algae) is False? A. They have flagellated cells B. Some have gametic meiosis, the same life cycle as humans C. They have chlorophyll C, a photosynthetic pigment D. Their bodies are largely made of silica E. Most of them are marine

D. Their bodies are largely made of silica

Diatom deposits, "diatomaceaous earth"

Diatom beds are mined for industrial uses: Filtering liquids in sugar refining, beer and wine making; insulation; toothpaste; nanotechnology... and killing insect pests

Bacillariophyta (a.k.a. Diatoms)

Diatoms live in glass houses: silica-based (SiO2) pill boxes Two major types: Centric & Pennate Centric: Radial symmetry; float; mainly planktonic and marine Pennate: Bilateral; bottom dwelling, on vegetation, also planktonic • Marine and freshwater habitats • 10,000 - 12,000 living species • Unicellular or colonial ca. 20 - 25% of global carbon fixation - (approximately equivalent to all of the terrestrial rain forests combined) Diatom cell wall = frustule (L: "frustulum" dim. = bit, piece) • Two overlapping halves (cell walls) • Primarily silica (SiO2) • Asexual reproduction by cell division

Some Dinoflagellates Are Involved In A Key Symbiosis In the Oceans -- Coral

Dinoflagellates known as "zooxanthellae" Reside in the endoderm of cnidarians (animals) and provide them with the products of photosynthesis; they receive inorganic nutrients Coral bleaching is caused by the loss (or expulsion) of zooxanthellae

Fungal Endophytes Can Protect Plants From Biotic Challenges

Dollar Spot Disease Moellerodiscus homoecarpa, an Ascomycete (grass is dead) Endophytes (both Ascomycetes) Epichloe typhina, Neotyphodium typhinum (grass is healthy) Theobroma cacao presence of endophytes reduces mortality caused by pathogens and area of leaf damaged by pathogens Dichanthelium lanuginosum (grass, lives near hot springs in yellow stone) Presence of endophyte provides heat tolerance Endophytes can be used in agriculture and climate change: increased Tolerance to heat and cold stress and increased Drought tolerance

Which of the following is a difference in fertilization between Angiosperms and Gymnosperms? A. Angiosperm pollen has 3 cells, Gymnosperms have 5 B. Angiosperms lack archegonia, Gymnosperms have them C. Angiosperms have polar nuclei, Gymnosperms do not D. Angiosperms form a triploid endosperm, Gymnosperms do not typically E. All of the above

E. All of the above

Which option best characterizes the pollination system of "basal angiosperms"? A. Hummingbird, copious nectar B. Bees, UV patterns, blue flowers C. Bats, white/green flowers, musky D. Lizards, red nectar E. Beetles/flies, deceit pollination

E. Beetles/flies, deceit pollination

Which of the following is FALSE about phloem in Angiosperms? A. Living cells that transport food materials throughout the plant B. Phloem consists primarily of sieve tube elements, which lack organelles C. Sieve tube elements rely on companion cells to carry out metabolic functions D. Phloem transports signalling molecules and is sometimes called the "superinformation highway" of plants E. Phloem cells are produced by the protoderm (primary meristem) and cork cambium (secondary meristem)

E. Phloem cells are produced by the protoderm (primary meristem) and cork cambium (secondary meristem)

Primary Growth

Extension of plant body (root or shoot) and formation of primary tissues (dermal, vascular, and ground tissues) Arise from apical meristems

(Most) Red Algae Have No Flagellated Cells!

Flagellated cells would normally appear in two contexts 1. Unicellular algae 2. Male gametes Red algae are Oogamous so have male gametes that differ from female gametes but those male gametes are not flagellated like most sperm Unicellular red algae and male gametes have limited amoeboid movement but no flagella. Most of their movement is passive in water currents

examples of secondary endosymbionts to know

Formal Clade Name, Common Name Haptophyta, Coccolithophores Dinoflagellata, Dinoflaggelates Bacillariophyta, Diatoms Phaeophyta, Brown Algae

Monocots and Dicots

Formerly these were considered phylogenetically distinct groups A couple of major differences: Monocots: One Cotyledon, Parallel leaf ventilation Dicots: Two Cotyledons, Netlike Leaf venation Cotyledon = embryonic leaf that comes up in shoot (so monocots just have a grass like shoot, dicots have a shoot with two leaves) The Dicots are NOT a monophyletic group (but the monocots are) Dicots = basal dicots + eudicots (paraphyletic) Monocots ~ 90,000 species (orchids, grasses, bamboo, scallions) Eudicots ~ 200,000 species (everything else)

The Anther

Four Microsporangia in Two Pairs Microspore mother cells divide via meiosis to form tetrads of haploid pollen grains Anther sacs rupture at the junction of the two pairs of microsporangia In gymnosperms, the microsporangia are in the cone

Fungal Endophytes: What Are They?

Fungi that live and grow within a host plant without causing disease (asymptomatic) All plants investigated thus far contain endophytes Endophytes feed on carbon produced by the plant Most frequently members of the Ascomycota

Red Alga Life Cycles Are Often More Complicated... Polysiphonia (and most red algae) has 3 generations

Gametophyte (n) Carposporophyte (2n) Tetrasporophyte (2n) haploid gametophyte makes gametes, fertilization results in carposporophyte which is a polyp on the gametophyte, carposporophyte produces diploid carpospores, germinate into tetrasporophyte, makes haploid tetraspores, germinate to gametophyte The Gametophyte And Tetrasporophyte Closely Resemble One Another = Isomorphic Gametophytes are haploid, and produce gametes by mitosis Diploid Carposporophyte remains attached to the female gametophyte (sort of like in bryophytes) The Carposporophyte is considered a separate diploid generation because it developes into a multicellular structure via mitosis This contrasts with Porphyra where the zygote immediately divides to produced spores Two diploid sporophyte generations! Haploid tetraspores germinate and develop into gametophytes male and female gametophytes (unisex)

rapid diversifacation and insects

Gaston de Saporta Proposed That The Rapid Diversification of Angiosperms Could Be Related to Their Relationships With Insects for Pollination Co-radiation of Angiosperms and Major Insect Pollinator Groups (both saw a great increase in diversity at the same time)

Flowers Can Be Inconspicuous

Grasses and other wind-pollinated species Showy parts can be leaves, not petals (poinsettia) Catkins of Trees (also wind-pollination) Self-fertilizing Species

Stramenopiles (= Heterokonts)

Heterokont refers to the fact that the motile stage of the life cycle has two differently-shaped flagella Tinsel flagellum with little branches wiplash flagellum, no branches Bacillariophyta (diatoms) Phaeophyta (brown algae)

Fungal Endophytes: How Diverse Are They?

How are they characterized? Isolation and morphology Identification Via DNA Arnold and Lutzoni 2007 Ecology All 28 plant species contained endophytes 1403 endophyte strains sequenced from 28 plant species 277 endophyte species recovered from the 1403 strains 50% of endophyte species (138 species) were found only once across all samples! More diversity near equator than near poles (more diverse at lower latitudes)

Or Did Pollinator Shifts Contribute More Importantly To Rapid Angiosperm Diversification?

In a different part of the plant's range, a longer tongued visitor becomes the primary pollinator, longer spurs are then selected for. In the remainder of the range, the shorter tongued visitors remain the primary pollinator This model suggests a punctuated change due to a pollination shift

Angiosperm life cycle:

In both angiosperms and gymnosperms meiosis results in microspores and megaspores In gymnosperms, microsporangia are borne in cones or strobili In angiosperms, microsporangia are borne in flowers Extreme reduction of the gametophyte

Photosynthetic Adaptations

In photosynthesis carbon is fixed in the process of synthesizing simple sugars (calvin cycle) Carbon dioxide enters through stomata Carbon is fixed by RuBisCo producing three-carbon compounds Three Photosynthetic Pathways: C3, C4, CAM

Who Pollinates Basal Angiosperms?

Insect pollination occurred very early in Angiosperm evolution Flies are most likely the first pollinators of Angiosperms Beetle pollination also arose very early Evidence From New Jersey ca. 90 mya fossils (Cretaceous) Cretaceous Flower With Close Similarities To the Giant Amazon Water Lily (Nymphaeaeceae), a Basal Angiosperm Beetle pollination involves insect entrapment (opens white, gives strong perfume that attracts beetles, beetles bring pollen. Closes and turns pink, traps the beetle inside for 24 hours, the flower then produces pollen and covers the beetle. Opens again and releases beetle with pollen, closes one last time)

Discovery of Porphyra life cycle in 1949 enabled commercial cultivation

Kathleen Drew Baker discovered the conchocelis phase in the life history of Porphyra Kathleen Drew Baker 1901 - 1957

Brown Algae - The Kelps

Kelps are large, highly differentiated brown algae, attached to rocks in a marine environment. Sporic Meiosis Laminaria, showing blade and stipe Laminaria, showing stipes and holdfast Macrocystis - giant kelp Grows in kelp forests Can grow 2 feet per day! Kelp forests are home to many marine animals

Journalism (Non-scientific audience)

LDR (lead and nut, development, resolution) The lead: Used to catch the reader's interest. May introduce drama, a human element, humor, or current event. Should contain the most interesting part of the story. The nut graph: (in-a-nutshell paragraph): An overview of the essence of the article, almost like an abstract. Includes some of the who, what, why, where, when, how, but is not comprehensive. Circularity, But More: The same applies to articles for non-scientific audiences. The writer will typically revisit the premise of the article at the end. They will also often illustrate how story has moved from the original starting point. Connecting the Conclusion to the Lead paragraph style: Must communicate in short paragraphs (even shorter than a scientific article) that have clear and distinct messages. Typically a paragraph communicates one thought or idea. Citing the Science and Researchers

Bioluminescence of Dinoflagellates

Light production by dinoflagellates occurs when there is some mechanical disturbance to them Disturbance may be caused by their predators (e.g. shrimp) Light they cast on their predators can attract other predators (e.g. cuttlefish)

Body Plan of a Dicot Seedling

Meristem: region of undifferentiated tissue, where a concentration of cell divisions occur shoot apical meristem at top, between cotyldons (2 leaves) root apical meristem right at bottom

C3 Pathway

Most of Earth's Plant Biomass is C3 plants C3 plants employ only the Calvin cycle (C3 pathway) in the fixation of CO2. • First stable product is a three-carbon compound • Rubisco: enzyme that catalyzes initial reaction of Calvin cycle - fixation of CO2. Rubisco can bind also to O2, in which case photorespiration starts. • Photorespiration is a wasteful process yielding neither energy nor fixed carbon

Climate change and vegetation along elevational gradients

Mount Abraham, Vermont Northern hardwood (conifer) range has shrunk, only at higher altitudes now Boreal range has grown, the trees are found at higher altitudes than in previous years

Structure of Scientific Papers

OCAR (opening, challenge, action, resolution) opening: What is the larger problem you are addressing? What do you need to understand to follow the story? challenge: What specific question do you propose to answer? What important gap does your work fill? Why is the work important? action: What did you do to address the challenge? What did you find? resolution: How can the issues raised in the opening be viewed differently in light of what you found?

Is Coevolution Between Plants & Pollinators The Cause of Rapid Angiosperm Diversification? Or Did Pollinator Shifts Contribute More Importantly To Rapid Angiosperm Diversification?

Other analyses indicate that changes in spur length occurred in a punctuated fashion, not continuous and gradual Therefore, they suggest that pollinator shifts, not continuous coevolution was the cause of diversification in this genus likely both occur, but pollinator shift is more common

Simple Tissues of Ground Tissue

PARENCHYMA: Most abundant cell type in plants; Thin walled cell; Perform basic housekeeping functions: respiration, storage, sometimes photosynthesis COLLENCHYMA: Unevenly thickened cell walls, Rubbery or stretchy material, Provide flexible support SCLERENCHYMA: May or may not be living at maturity, Thickened cell wall, Can be short (sclerids) or long and narrow (fibers), Provide structural support

complex tissues of phloem

Phloem: Living cells that transport food materials and signaling molecules "superinformation highway" of plants The sieve-tube members are alive, yet they lack organelles like the nucleus or ribosomes. Sieve tube elements rely on organelles from the companion cells. The companion cell carries out all metabolic functions of the sieve-tube member.

Primary Endosymbiosis

Photosynthesis in eukaryotes evolved via the transfer of a cyanobacterium to some ancient, nonphotosynthetic alga

Phytoplankton

Photosynthetic algae and cyanobacteria suspended in bodies of fresh or salt water Beginning of the food chain for heterotrophic organisms that live in water (e.g. fish, whales, etc.) ~ Half of "plant" biomass on the planet Marine phytoplankton absorb ~ 50% of CO2 produced by humans

A Test of These Hypotheses in the Columbine Genus (Aquilegia) (pollinator shift vs coevolution)

Pollination syndromes are related to floral traits 10 Floral traits were measured on each of 27 Columbine species The figure shows a Principal Components Analysis. PC1 and PC2 are new variables that extract the major sources of variation in the 10 traits 1. Species with the same pollination syndrome have similar flowers 2. PC1 differentiates hawkmoth pollinated species from the others 3. PC2 differentiates bumble bee from hummingbird pollinated species Pollination syndromes are related to nectar spur length Nearly non-overlapping distribution of spur lengths among pollination syndromes Phylogeny shows TWO types of transitions, with no/few reversals (bee flowers transition to hummingbird flowers, hummingbird flowers to hawkmoth flowers)

Red Algae Life Cycles Have An Alternation Of Generations Porphyra

Porphyra has a biphasic alternation of generations (i.e. has 2 different generations just like green land plants) gametophyte is leaf blade, produces gametes which fuse to form zygotospores (2N), zygotospore attaches to shell substrate, forms conchocelis (filamants 2N), produces conchospores (2N), conchospore anchors ro ground and undergoes meiosis, then forms gametophyte (N) Gametophyte is a genetic chimera gametophyte is male or female (unisex)

Pseudoparenchyma

Pseudoparenchymatous algae are made up of a loose or close aggregation of numerous, intertwined, branched filaments that collectively form the thallus, held together by mucilages, especially in red algae. Pseudoparechyma superficially resemble parenchyma. Heribaudiella, a crustose alga clinging to rocks in a stream. Pseudoparenchyma in a brown alga (next lecture). Note the tightly packed filaments

What Characterizes The Flowers Of Basal Angiosperms ?

Radially symmetric • Typically white or red/maroon • Pollinators receive pollen as reward, rarely nectar

Photosynthetic Organisms Of Aquatic Environments, Especially Oceans

Red algae are common in oceans near shorelines, in intertidal zones But what are the PHYTOPLANKTON in oceans? How did they become photosynthetic?

"Mother of the Sea" -- Kathleen Drew Baker

Revolutionized the cultivation of nori by discovering that Conchocelis rosea wasn't a separate species but part of the Porphyra life cycle (called the "conchocelis phase"). Previously, the Porphyra life cycle could not be completed in aquaculture. Paper published in Nature in 1949 Published 47 papers, mostly on red algae Co-founder and first president of the British Phycological Society In Japan, alone, the nori industry is valued at over $2 billion because it is now possible to complete the life cycle in cultivation Drew-Baker did her groundbreaking research as an unpaid research fellow. She was fired from her teaching position at the University of Manchester when she married in 1928. The University had a policy against employing married women. Her husband helped build a tidal tank in her (unfunded) laboratory where she collected her specimens in old jam jars. April 14 is "Drew Day" celebrated by Japanese nori farmers

All Red Algae Were Thought To Be Photosynthetic Until Major New Finding in August 2019

Rhodelphidia is a newly-described phylum These red algae are completely unlike other red algae: 1. Non-photosynthetic predators 2. Have flagella 3. Gene-rich genome with many introns Evolutionary Implications of New Finding Ancestor of red algae inferred to be "mixotropic" meaning that it conducted both phagotrophy and autotrophy The absence of phagotrophy in nearly all Archaeplastida resulted from multiple convergent losses rather than an already established ancestral state

What Makes An Idea "Sticky"?

SUCCES simple, unexpected, concrete, credible, emotional, stories Translating Science: Connecting To The Audience

science writing vs non-science writing

Scientific Audiences Are Patient Scientists are accustomed to reading the opening, challenge, and action before finding out about the resolution. But it takes a long time... Non-Scientific Audiences Are Impatient In journalism, science is communicated with a different structure where the story is collapsed and presented up front, in a very brief way without details Then, the journalist backs up and drills deeper with more context

watermelon snow and climate change

Snow algae communities inhabit snow and ice surfaces — bloom during the melt season Factors That Constrain Snow Algal Abundance: Liquid water, Nutrient availability, Temperature Chlamydomonas nivalis is one key species of snow algae Glacier microbiomes contribute to lowering albedo, accelerating melt (Albedo is the reflection of the sun's rays; watermelon snow is pink/red and not white, so less sun is reflected and more ends up melting)

Leaves

Stomata = openings in epidermis that allow for gas exchange Epidermal cells covered with cuticle to minimize water loss

Secondary Growth Is An Important Adaptation

Strengthening and thickening of roots allows for more extensive root systems Mesquite roots have been found at a depth of 53.3 meters (ca. 175 feet) Most roots are near surface and absorb rain water Deep taproots access ground water during drought Minnesota Prairie Biomass greater below-ground than above-ground Extensive root systems allow plants to survive where drought is prevalent

Can Endophytes Affect Plant Community Structure?

Tall Fescue (Festuca arundinacea) Native to Eurasia and North Africa Exotic to North America Endophyte (Neotyphodium coenophialum) Vertically transmitted among plants: The fungus is transmitted from parent to offspring via the seed Some plants are infected, others are not Keith Clay and Jenny Holah Indiana University Botany Experimental Field Half of plots seeded with endophyte infected fescue grasses (+E) Half of plots seeded with endophyte uninfected fescue grasses (-E) Treatment Effects on Overall Plant Biomass = no significant effect on total plot biomass Treatment Effects on Biomass of Fescue vs. Other Grasses = grasses with endophyte made up higher proportion of plot biomass Treatment Effects on Plant Species Richness = plots that had grasses with endophytes had lower species richness (endophyte made grass more competitive, it over competed some other species)

Fungal Endophytes & Medicine

Taxol & Cancer Taxol used as treatment, harvested from bark of pacific yew Harvesting & Conservation Concern Not the bark of yew that made taxol, it was an endophyte At least 18 different fungal genera produce taxol A large number of other secondary metabolites have been isolated with anti-cancer properties (includes terpenoids, alkaloids, etc.)

Stepping Stone Model of Pollinator Shifts

The authors argue that the evolution from bee to hawkmoth pollination requires an intermediate step of hummingbird pollination as there are no transitions directly from bee to hawkmoth Aquilegia occurs in Eurasia But there are no hummingbirds in Eurasia If there are no intermediates then can hawkmoth pollination evolve in Eurasia? There is no known Aquilegia species in Eurasia pollinated by hawkmoths

Structure of the female gametophyte in angiosperms

The central cell in the female gametophyte is binucleate 3 antipodals on top, 1 large center cell with two polar nuclei, 2 synergids surrounding 1 egg cell next to micropyle Micropyle on bottom, pollen tube has to enter on top and go around to the bottom

The Evolution of Self Pollination

The evolution of self pollination from cross pollination (i.e. outcrossing) is considered to be one of the most common evolutionary transitions in flowering plants In many environments the supply of pollinators is uncertain and therefore reproduction might fail to occur 1. Colonizing species ("weedy" species) 2. Marginal habitats - edge of a species' range 3. Annual life history (life cycle occurs in one year) Many "Weedy" Annual Plants Are Highly Selfing (arabidopsis)

Rhodophyta, the Red Algae

The red algae come in many forms, from unicellular forms, to filaments with apical growth, to large blades made of filaments, to true parenchyma.

Who are the closest ancestors of the Angiosperms?

The relationship of gymnosperms to angiosperms is still unclear Two alternative views: Anthophyte Hypothesis: One view based on morphological data -Gymnosperms are not a monophyletic group -Gnetophytes are most closely allied (related to angiosperms) [cycads outgroup, then ginkgo, then pinaceae and cupressophytes are sisters and gnetophytes and angiosperms sisters] Gnepine Hypothesis One view based on DNA sequence data -Here Angiosperms and Gymnosperms are both monophyletic groups -Gnetophytes are most closely related to Pines -No extant close relatives to Angiosperms [angiosperm outgroup, then cycads, ginkkgo, cupressophytes, and pineceae and gnetophytes are sisters]

Root Apex: The Root Cap

The root apical meristem is subapical and is covered by a root cap. Functions of the root cap include: • Protection of the apical meristem • Production of mucigel and border cells (sloughed root cap cells)

Darwin's 'Abominable Mystery'

The sudden origin, rapid diversification, and rise to dominance of flowering plants Darwin suggested that perhaps there was a long unrecorded history of Angiosperms prior to the Cretaceous "I have fancied that perhaps there was during long ages a small isolated continent in the S. hemisphere which served as the birthplace of the higher plants — but this is a wretchedly poor conjecture."

secondary growth

Thickening of the root and stem Arise from lateral meristems

Is Coevolution Between Plants & Pollinators The Cause of Rapid Angiosperm Diversification?

This model suggests a gradual increase in nectar spur length due to ongoing coevolution with the same pollinator Ex: moths with longest tongues selected for because they get greatest reward, plants with longest spurs are selected for because the pollinators body comes in closest contact with reproductive organs Darwin's orchid and the moth with the really long tongue

Primary Growth of Stem

Three primary meristems make the three tissue systems apical meristem makes primary meristems (protoderm, ground meristem, procambium) protoderm makes dermal tissue ground meristem makes ground tissue procambium makes vascular tissue

Secondary Endosymbiosis

We won't discuss secondary endosymbionts of the green algae All Phytoplankton we will discuss are secondary endosymbionts of red algae Dinoflagellates (alveolata), haptophytes, and diatoms (stramenopilia) In secondary endosymbiosis, a plastid has been acquired by engulfing another eukaryote that already has a plastid. The engulfed organism becomes an organelle and is essential for life Secondary endosymbiosis has resulted in an enormous diversity of life Plastids from green and red algae have been transmitted to many other eukaryotes

The Evolution of Wind Pollination

What Floral Traits Are Associated With Wind Pollination? many flowers, many pollen grains, unisexual flowers, open habitats (like prairies) Ragweed, oak, bamboo, grasses

Discussion of "Tiny Plants That Once Ruled the Seas"

What key event affected marine biodiversity ~250 mya? And what change in algae did it correspond with? A mass extinction event occurred; green algae were dominant before the extinction, but red algae took over after the extinction What do nutrients have to do with the changes in marine diversity, especially algae? The nutrient run off was more well suited for red-algae, which is why red algae flourished (nitrogen, phosphorus) How might the legacy of high carbon dioxide emissions affect some of these organisms? They cannot adapt quickly enough, they are dying off

When Animal Pollinators Are Unreliable, Many Plant Species Have Shifted Their Reproductive Strategy

When there are pollinator limitations, evolution to wind pollination (in windy environments), switch to self fertilization, or switch pollinators These changes have occurred repeatedly throughout the history of Angiosperms

Complex Tissues of xylem

Xylem: conduction of water and nutrients; support Tracheids - Elongated cells, no perforations Have pits (pores) through which water travels between tracheids Vessel Elements - Elongated cells, with perforations Found primarily in angiosperms Efficient flow of water between vessel elements

Ovule Develops Into Seed Ovary Develops Into Fruit

Zygote -> Embryo (2N) = new Sporophyte Sperm + 2 polar nuclei -> Endosperm (3N) = nutrient tissue Ovary -> Fruit: Enclosed seed is not naked as in the gymnosperms Gymnosperm (Gr. "naked seed") Angiosperm (Gr. "vessel or box"+ "seed") Seed has seed coat, 3n endosperm, and 2n embryo. Fruit surrounds seed (ovary)

Star Anise

a basal angiosperm Shikimic acid is a precursor for Tamiflu, An antiviral sometimes used to treat influenza Five-spice powder, used in some Chinese cooking Pho, Vietnamese noodle soup

Fungal Endophytes: How Do They Affect Plants?

benefit vs quantity of endophyte As quantity of endophyte grows, benefits increase and then plateau. Direct costs increase linearly. Net effect = benefits - costs positive outcome = mutualism 0 = threshold for shift from mutualism to antagonism negative outcome = parasitism

Fungal Endophytes: Benefits Depend On Environment

can provide resistance to pathogens, herbivores, or abiotic stress in Absence of Stressors: no benefit to plant, all costs in Nutrient Limitation: some benefit, but more cost to plant

phylogeny and # of species of land plants

charophytes (land plants) liverworts (8500) mosses (10,000) hornworts (100) (vascular plants) lycophytes (1200) ferns (12,000) (Seed plants) cycadophyta (300) ginkgophyta (1) gnetophyta (90) coniferophyta (700) angiosperms (300,000)

Red Algae (Rhodophyta) Are Members of the Archaeplastida

glaucophytes, red algae, green algae (2 branches), land plants

comparison of chloroplasts in archaeplastida

glaucophytes: Chloroplasts (called cyanelles) - retain peptidoglycan - retain phycobilisome rhodophytes (red algae) lose peptidoglycan - retain phycobilisome green plants: lose peptidoglycan - lose phycobilisome - stack thylakoids

Climate Change & Species Distributions

most of the tree diversity in america is east of the mississipi river, and south Under projected climate change, suitable habitat will dramatically shift north change in species distribution due to temperature and precipitation

kelp forest demise

sea star wasting disease killed many sea stars, an important predator heatwave warmed ocean explosion of purple sea urchin population sea urchin ate all the kelp, out competed other animals that eat kelp (red abalone die off; red abalone harvested by humans)